Different positioning of the ligand-binding domain helix 12 and the F domain of the estrogen receptor accounts for functional differences between agonists and antagonists.
The estrogen receptor is capable of binding a diverse set of ligands that are broadly categorized as agonists or antagonists, depending on their abilities to induce or interfere with transcriptional responsiveness. We show, using a fusion protein assay for ligand-binding which does not rely on transcriptional responsiveness, that agonists and antagonists differently position the C-terminus of the ligand-binding domain (helix 12) and the F domain. Upon antagonist binding, the F domain interferes with the fusion protein activity. Mutational disruption of helix 12 alters the position of the F domain, imposing interference after agonist or antagonist binding. Genetically selected inversion mutations where only agonists, but not antagonists, induce interference are similarly reliant on helix 12 and F domain positioning. Our results demonstrate that agonists and antagonists differently position helix 12 and implicate the F domain in mechanisms of antagonist action.
Nichols
M
M
Gene Expression Program, EMBL, Meyerhofstrasse 1, 69117, Heidelberg, Germany. Nichols@embl-heidelberg.de
Rientjes
J M
JM
Stewart
A F
AF
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics / Q000502:physiology; D019556:COS Cells; D004254:DNA Nucleotidyltransferases / Q000235:genetics; D004965:Estrogen Antagonists / Q000378:metabolism / Q000494:pharmacology*; D008024:Ligands; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics / Q000502:physiology; D016716:PC12 Cells; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D011960:Receptors, Estrogen / Q000819:agonists* / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship
D004965:Estrogen Antagonists; D008024:Ligands; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; D004254:DNA Nucleotidyltransferases; C045119:FLP recombinase